In Reply.—In reporting our case of fatal pericardial tamponade caused by perforation of the right ventricle by a dialysis catheter, we tried to offer some advice concerning safeguards in the use of this valuable technique.Dr Patel offers an additional means of diagnosing this serious complication. Although cardiac ultrasonography may indeed be an extremely valuable diagnostic procedure, we cannot enthusiastically recommend it in this situation for the following reasons.The equipment necessary to do ultrasonography, particularly two-dimensional real-time ultrasonography, may not be generally available in smaller institutions as yet. Even if it is available, the equipment requires a skilled technician and a cardiologist specifically trained in this technique to make the procedure useful. Although cardiac ultrasound may demonstrate the catheter in the cardiac chambers, the demonstration of the exact location of the catheter tip is sometimes difficult. Although cardiac ultrasound may demonstrate small amounts of pericardial fluid, pericardial tamponade